Chemistry, NIT-PHL
How do you use raw plant materials to manufacture a best-selling perfume? How do you engineer household products that are compliant with environmentally-oriented guidelines? The answers to these questions require an understanding of the laws of chemistry, the science that deals with the properties, composition, and structure of elements and compounds, as well as the transformations that such substances undergo and the energy that is released or absorbed during those processes. Chemistry is also concerned with the utilization of natural substances and the creation of artificial ones. Over time, more than 8,000,000 different chemical substances, both natural and artificial, have been characterized and produced. Chemistry's vast scope comprises organic, inorganic, physical, analytical, and industrial chemistry, along with biochemistry, environmental chemistry, medicinal chemistry, and much more. Through the dedicated efforts of people such as Robert Boyle, Dmitri Mendeleev, John Dalton, Marie Curie, and Rosalind Franklin, the field of chemistry has led to exciting innovations as well as crucial advances in our understanding of how the world functions, starting with the miniscule and unassuming atom.
Chemistry Encyclopedia Articles By Title
nitrobenzene
nitrobenzene, the simplest aromatic nitro compound, having the molecular formula C6H5NO2. It is used in the manufacture......
nitrocellulose
nitrocellulose, a mixture of nitric esters of cellulose, and a highly flammable compound that is the main ingredient......
nitrogen
nitrogen (N), nonmetallic element of Group 15 [Va] of the periodic table. It is a colourless, odourless, tasteless......
nitrogen dioxide
nitrogen dioxide, inorganic compound, a highly reactive and poisonous gas. Nitrogen dioxide is one of several nitrogen......
nitrogen group element
nitrogen group element, any of the chemical elements that constitute Group 15 (Va) of the periodic table. The group......
nitroglycerin
nitroglycerin, a powerful explosive and an important ingredient of most forms of dynamite. It is also used with......
nitroso compound
nitroso compound, any of a class of organic compounds having molecular structures in which the nitroso group (-N=O)......
nitrous acid
nitrous acid, (HNO2), an unstable, weakly acidic compound that has been prepared only in the form of cold, dilute......
nitrous oxide
nitrous oxide (N2O), one of several oxides of nitrogen, a colourless gas with pleasant, sweetish odour and taste,......
Noailles, Jean-Paul-François, 5 duc de
Jean-Paul-François, 5th duke de Noailles was the son of Louis of Noailles, a lieutenant general, and a member of......
Nobel, Alfred
Alfred Nobel was a Swedish chemist, engineer, and industrialist who invented dynamite and other more powerful explosives......
nobelium
nobelium (No), synthetic chemical element of the actinoid series of the periodic table, atomic number 102. The......
noble gas
noble gas, any of the seven chemical elements that make up Group 18 (VIIIA) of the periodic table. The elements......
Nocera, Daniel G.
Daniel G. Nocera is an American inorganic chemist known for inventing the first practical “artificial leaf,” a......
Noddack, Ida
Ida Noddack was a German chemist who codiscovered the chemical element rhenium and who first proposed the idea......
nonmetal
nonmetal, in physics, a substance having a finite activation energy (band gap) for electron conduction. This means......
nonstoichiometric compound
nonstoichiometric compound, any solid chemical compound in which the numbers of atoms of the elements present cannot......
norepinephrine
norepinephrine, substance that is released predominantly from the ends of sympathetic nerve fibres and that acts......
Norrish, Ronald George Wreyford
Ronald George Wreyford Norrish was a British chemist who was the corecipient, with fellow Englishman Sir George......
Northrop, John Howard
John Howard Northrop was an American biochemist who received (with James B. Sumner and Wendell M. Stanley) the......
Novichok
Novichok, group of organophosphate chemicals that act as nerve agents and were designed for use as weapons of chemical......
Noyori Ryōji
Noyori Ryōji is a Japanese chemist who, with K. Barry Sharpless and William S. Knowles, won the Nobel Prize for......
Nuclease
Nuclease, any enzyme that cleaves nucleic acids by breaking phosphodiester bonds between nucleotide molecules.......
Nucleic acid
Nucleic acid, naturally occurring chemical compound that serves as the main information-carrying molecule of the......
nucleophile
nucleophile, in chemistry, an atom or molecule that in chemical reaction seeks a positive centre, such as the nucleus......
Nucleoprotein
Nucleoprotein, molecule consisting of a protein linked to a nucleic acid, either DNA (deoxyribonucleic acid) or......
Nucleoside
Nucleoside, a structural subunit of nucleic acids, the heredity-controlling components of all living cells, consisting......
Nucleotide
Nucleotide, any member of a class of organic compounds in which the molecular structure comprises a nitrogen-containing......
nylon
...
Nüsslein-Volhard, Christiane
Christiane Nüsslein-Volhard is a German developmental geneticist who was jointly awarded the 1995 Nobel Prize for......
Ocean Acidification: How Carbon Dioxide Is Hurting the Seas
The Keeling Curve is one of climatology’s most enduring and useful tools. It’s a graph that has tracked seasonal......
octane number
octane number, measure of the ability of a fuel to resist knocking when ignited in a mixture with air in the cylinder......
octaves, law of
law of octaves, in chemistry, the generalization made by the English chemist J.A.R. Newlands in 1865 that, if the......
octet
octet, in chemistry, the eight-electron arrangement in the outer electron shell of the noble-gas atoms. This structure......
oganesson
oganesson (Og), a synthetic transuranium element with the atomic number 118 that is a member of the noble gases,......
Olah, George A.
George A. Olah was a Hungarian American chemist who won the 1994 Nobel Prize for Chemistry for work conducted in......
olefin
olefin, compound made up of hydrogen and carbon that contains one or more pairs of carbon atoms linked by a double......
Oleic acid
Oleic acid, the most widely distributed of all the fatty acids, apparently occurring to some extent in all oils......
Oligonucleotide
Oligonucleotide, a short chain of nucleotides (nitrogen-containing units linked to a sugar and a phosphate group)......
Oligosaccharide
Oligosaccharide, any carbohydrate of from three to six units of simple sugars (monosaccharides). A large number......
Onsager, Lars
Lars Onsager was a Norwegian-born American chemist whose development of a general theory of irreversible chemical......
Onslow, Muriel Wheldale
Muriel Wheldale Onslow was a British biochemist whose study of the inheritance of flower colour in the common snapdragon......
Oparin, Aleksandr
Aleksandr Oparin was a Russian biochemist noted for his studies on the origin of life from chemical matter. By......
organic chemistry
organic chemistry, field of science concerned with the composition, properties, and structure of chemical elements......
organic compound
organic compound, any of a large class of chemical compounds in which one or more atoms of carbon are covalently......
organohalogen compound
organohalogen compound, any of a class of organic compounds that contain at least one halogen (fluorine [F], chlorine......
organometallic compound
organometallic compound, any member of a class of substances containing at least one metal-to-carbon bond in which......
organosulfur compound
organosulfur compound, a subclass of organic substances that contain sulfur and that are known for their varied......
osmium
osmium (Os), chemical element, one of the platinum metals of Groups 8–10 (VIIIb), Periods 5 and 6, of the periodic......
Ostwald, Wilhelm
Wilhelm Ostwald was a Russian-German chemist and philosopher who was instrumental in establishing physical chemistry......
Ostwald, Wolfgang
Wolfgang Ostwald was a German chemist who devoted his life as a teacher, researcher, and editor to the advancement......
oxalic acid
oxalic acid, a colourless, crystalline, toxic organic compound belonging to the family of carboxylic acids. Oxalic......
Oxidation
Oxidation, chemical process in which an atom, ion, or molecule loses electrons as it interacts with another chemical......
oxidation number
oxidation number, the total number of electrons that an atom either gains or loses in order to form a chemical......
oxidation-reduction reaction
oxidation-reduction reaction, any chemical reaction in which the oxidation number of a participating chemical species......
oxide
oxide, any of a large and important class of chemical compounds in which oxygen is combined with another element.......
oxide mineral
oxide mineral, any naturally occurring inorganic compound with a structure based on close-packed oxygen atoms in......
Oxidoreductase
Oxidoreductase, any member of a class of enzymes, commonly known as dehydrogenases or oxidases, that catalyze the......
oxime
oxime, any of a class of nitrogen-containing organic compounds usually prepared from hydroxylamine and an aldehyde,......
oxyacid
oxyacid, any oxygen-containing acid. Most covalent nonmetallic oxides react with water to form acidic oxides; that......
oxygen
oxygen (O), nonmetallic chemical element of Group 16 (VIa, or the oxygen group) of the periodic table. Oxygen is......
oxygen group element
oxygen group element, any of the six chemical elements making up Group 16 (VIa) of the periodic classification—namely,......
Oxytocin
Oxytocin, neurohormone in mammals, the principal functions of which are to stimulate contractions of the uterus......
ozone
ozone, (O3), triatomic allotrope of oxygen (a form of oxygen in which the molecule contains three atoms instead......
ozonide
ozonide, any of a class of chemical compounds formed by reactions of ozone (q.v.) with other compounds. Organic......
ozonolysis
ozonolysis, a reaction used in organic chemistry to determine the position of a carbon-carbon double bond in unsaturated......
palladium
palladium (Pd), chemical element, the least dense and lowest-melting of the platinum metals of Groups 8–10 (VIIIb),......
pancreatic polypeptide
pancreatic polypeptide, peptide secreted by the F (or PP) cells of the islets of Langerhans in the pancreas. Pancreatic......
Paneth, Friedrich Adolf
Friedrich Adolf Paneth was an Austrian chemist who, with George Charles de Hevesy, introduced radioactive tracer......
pantothenic acid
pantothenic acid, water-soluble vitamin essential in animal metabolism. Pantothenic acid, a growth-promoting substance......
Papain
Papain, enzyme present in the leaves, latex, roots, and fruit of the papaya plant (Carica papaya) that catalyzes......
para-aminobenzoic acid
para-aminobenzoic acid (PABA), a vitamin-like substance and a growth factor required by several types of microorganisms.......
paraffin hydrocarbon
paraffin hydrocarbon, any of the saturated hydrocarbons having the general formula CnH2n+2, C being a carbon atom,......
parathion
parathion, an organic phosphorus compound well known as an insecticide that is extremely toxic to humans. The compound......
Parathyroid hormone
Parathyroid hormone (PTH), substance produced and secreted by the parathyroid glands that regulates serum calcium......
Parkes, Alexander
Alexander Parkes was a British chemist and inventor noted for his development of various industrial processes and......
Parsons, Jack
Jack Parsons was an American rocket scientist and chemist who made significant contributions to the development......
Pasteur, Louis
Louis Pasteur was a French chemist and microbiologist who was one of the most important founders of medical microbiology.......
Pauling on periodic law
American theoretical physical chemist Linus Carl Pauling (1901–94) is the only person to have won two unshared......
Pauling, Linus
Linus Pauling was an American theoretical physical chemist who became the only person to have won two unshared......
Payen, Anselme
Anselme Payen was a French chemist who made important contributions to industrial chemistry and discovered cellulose,......
Peacocke, Arthur
Arthur Peacocke was a British theologian, biochemist, and Anglican priest who claimed that science and religion......
Pectin
Pectin, any of a group of water-soluble carbohydrate substances that are found in the cell walls and intercellular......
Pedersen, Charles J.
Charles J. Pedersen was an American chemist who, along with Jean-Marie Lehn and Donald J. Cram, was awarded the......
Pelletier, Pierre-Joseph
Pierre-Joseph Pelletier was a French chemist who helped found the chemistry of alkaloids. Pelletier was professor......
Pepsin
Pepsin, the powerful enzyme in gastric juice that digests proteins such as those in meat, eggs, seeds, or dairy......
Peptide
Peptide, any organic substance of which the molecules are structurally like those of proteins, but smaller. The......
per- and polyfluoroalkyl substance
per- and polyfluoroalkyl substance (PFAS), any of a group of synthetic chemical compounds that contain fluorine......
periodic table
periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number—i.e.,......
Perkin, Sir William Henry
Sir William Henry Perkin was a British chemist who discovered aniline dyes. In 1853 Perkin entered the Royal College......
peroxide
peroxide, any of a class of chemical compounds in which two oxygen atoms are linked together by a single covalent......
peroxy acid
peroxy acid, any of a class of chemical compounds in which the atomic group ―O―O―H replaces the ―O―H group of an......
Perutz, Max Ferdinand
Max Ferdinand Perutz was an Austrian-born British biochemist, corecipient of the 1962 Nobel Prize for Chemistry......
PETN
PETN, a highly explosive organic compound belonging to the same chemical family as nitroglycerin and nitrocellulose.......
phase
phase, in thermodynamics, chemically and physically uniform or homogeneous quantity of matter that can be separated......
phenol
phenol, any of a family of organic compounds characterized by a hydroxyl (―OH) group attached to a carbon atom......
phenol-formaldehyde resin
phenol-formaldehyde resin, any of a number of synthetic resins made by reacting phenol (an aromatic alcohol derived......
Phenylalanine
Phenylalanine, an amino acid present in the mixture obtained upon hydrolysis of common proteins. Human hemoglobin......
pheromone
pheromone, any endogenous chemical secreted in minute amounts by an organism in order to elicit a particular reaction......
phlogiston
phlogiston, in early chemical theory, hypothetical principle of fire, of which every combustible substance was......